1. Technical Field
The present invention relates to a printing system, a printing method, and a non-transitory computer readable recording medium stored with printing program, for printing a color image.
2. Description of Related Art
In recent years, in the color printing industry, on-demand-printing equipment such as an electro photographic printer and an inkjet printer has become more widely utilized. Therefore, color calibration is increasingly important for maintaining printing quality of the printing equipment.
Regarding color calibration of the printing equipment, a known technique applies one-dimensional curves (one-dimensional LUTs: one-dimensional lookup tables) for each of base colors of C (cyan), M (magenta), Y (yellow) and K (black) to calibrate the gradation of each base color. The color calibration using one-dimensional LUTs allows small calculation load and provides processing in a short time, but it cannot accommodate a big change in superposition balance of a plurality of base colors due to a change of printing environment or material's lot. For this reason, a color calibration using multi-dimensional LUT such as three-dimensional or four-dimensional LUT has been proposed from the viewpoint of keeping the superposition balance of a plurality of base colors consistent (for example, Unexamined Japanese Patent Publication No. 2007-089031). Since color calibration using the multi-dimensional LUT has a heavy calculation load, such color calibration is usually performed simultaneously with a rasterizing process (a RIP process) to the print data described in page description language (PDL) to reduce processing time.
On the other hand, in the production of printed matter, a sample for proofreading is usually printed before printing the required number of copies. Then, the required number of copies are printed after final proofreading of the sample for proofreading. Therefore, the image data obtained by performing the RIP process to the print data at the time of printing the sample for proofreading is stored in a hard disk, and the image data is read from the hard disk and is reused at the time of printing the required number of copies. According to such constitution, it is not necessary to perform the RIP process to the print data again at the time of printing the required number of copies, and processing time is reduced.
However, the printing environment may be changed after printing the sample for proofreading before printing the required number of copies, and it may be necessary to change calibration conditions. In cases where the calibration conditions need to be changed, LUT for calibration is newly generated. In the printing system which performs the color calibration using the multi-dimensional LUT, the color calibration is performed simultaneously with the RIP process, therefore it is necessary to perform the RIP process to the print data again to regenerate the image data, in order to perform the color calibration by applying the newly generated LUT and to print the required number of copies. However, this causes processing time to be long and it is not preferable.